I made 3 version based around a Ntag215: NFC Coin, NFC keychain, and Wifi embossed version. The thick coin is meant to resist metal interference if you stick it to a metal surface. Through my testing it worked 90% of the time. The internal cavity is 25.5x1.25mm. The raw tag I received measure 25.1x1mm.

Designed around pausing the print, drop in the coin and then resume the print.

If you have additional version you want, comment and I will see what I can do.